Yukos:
Let's assume the pressure in space is zero. If that is the case (and I believe it's pretty close to zero, if not zero) then the boiling point doesn't exist, because liquid water can't exist.
Take a look at a phase diagram, like this one:
http://wine1.sb.fsu.edu/chm1045/notes/Forces/Phase/Forces06.htm At pressures below the "triple point" of water, liquid water can't exist. If you took a glass of water out of a space capsule, the water would almost instantly evaporate, or "boil."
As you can see from the phase diagram, the boiling points and sublimation points of substances change with changing pressure.
At very low pressures, below 4.58 torr, ice would behave the same way "dry ice" behaves -- when temperatures get high enough, it sublimates to become vapor without going through a liquid phase.